How Breast Cancer Stages Affect Your Prognosis

The severity of your breast cancer, known as its stage, can be determined by a variety of tests after the initial diagnosis. Staging breast cancer is important because the treatment options your doctor may recommend to you depend on if the cancer has metastasized (spread), and if so, how far. Specific requirements must be met for the cancer to be classified as a specific stage. Many factors are evaluated during the staging process, such as the size of your tumor.

Stage 0 breast cancer

This is also known as carcinoma in situ, and there are two sub-categories of this for breast cancer. According to the National Cancer Institute, ductal carcinoma in situ (DCIS) is a non-invasive disease where abnormal cells are discovered in the breasts’ ducts. Lobular carcinoma in situ (LCIS) is similar to DCIS, however the abnormal cells are found in the lobules of the breast. Both conditions have the potential to become invasive cancer over time.

Stage I breast cancer

According to the Mayo Clinic, this stage is reached if the tumor is less than two centimeters long, which is about the same length as a peanut. Also at this stage, the cancer hasn’t spread to the lymph nodes or anywhere outside the breasts.

Stage II breast cancer

In this stage, the cancer may have spread to the lymph nodes, but it hasn’t left the breast yet. If the tumor is bigger than five centimeters but hasn’t spread to the axillary lymph nodes, it can be called stage IIA. Stage IIB can be classified if the tumor is less than two centimeters in diameter but cancer is present in up to three axillary lymph nodes.

Stage III breast cancer

Though not yet spread to distant parts of the body, in this stage, the cancer may have spread to areas immediately near the breasts, such as lymph nodes under the arm or next to the collarbone. If that’s the case, a stage IIIA classification can be made if the nodes aren’t attached to each other and the tumor is bigger than five centimeters. If the tumor is smaller than five centimeters, but cancer has spread to the lymph nodes next to the collarbone, it is known as stage IIIB.

Stage IV breast cancer

If this stage of breast cancer is diagnosed, the patient’s prognosis is relatively poor. This is the most advanced stage breast cancer can reach, and it is signified by the cancer spreading to distant tissues and organs of the body, such as the brain or lungs. This stage is often referred to as metastatic breast cancer.